This invention relates to vehicle alignment apparatus, and more particularly to such apparatus utilizing battery powered sensors.
Apparatus for aligning vehicle wheels typically use sensors mounted at each wheel and a central console (or a handheld remote unit) which receives and manipulates data from the sensors. Communication between the sensors and the console (or remote unit) is conventionally accomplished over electrical cables. In those systems, the cables also provide power for the sensors. Cables, however, do have certain drawbacks. They tend to get in the way, they must be physically installed by the user, and their length is fixed (requiring consistent placement of the vehicle).
Cableless alignment systems have been designed, but they require some means of providing power for the sensors at each wheel. Batteries are used to provide this power, but batteries come with their own drawbacks. For example, although batteries can be recharged, it is inconvenient for a user of alignment equipment to stop an alignment procedure in mid-procedure to recharge or replace a battery. The technician often is not aware until too late that the battery needs to be recharged. Moreover, although the discharge state of a battery can be measured, that measurement is generally analog, while communications between the sensors and the console in cableless systems is almost exclusively digital.
With conventional battery-powered sensor alignment systems, the act of (re)charging the batteries requires the technician/user to perform a separate operation (which may involve throwing a switch, or may be more complicated), and the technician/user does not always remember to perform that operation at the proper time. Rechargeable batteries also require special handling to promote battery life. Deep discharge can shorten battery life, as can recharging using relatively simple recharging schemes.